#include <chrono>
#include <iostream>
using namespace std::literals::chrono_literals;

struct Duration {
  std::chrono::milliseconds millis_;
};

void example() {
  auto d = Duration{};
  d.millis_ = 100ms;

  auto timeout = 1s;
  d.millis_ = timeout; // ok, second will be converted to millisecond
  // so d.millis_ = 1000ms?
}

int main() {
  example();
}
